Biology

Physiology

Cloyster has a large shell covered in spikes. Six of the spikes are long and conical, resembling turrets, and are used to protect its soft insides from foes. However, the shell offers a lack of protection against special attacks. Cloyster has an inner, gray-colored layer inside its purple shell. Its "head" and face resemble a black pearl, and there is a jutting, horn-like white spike above its "head". Its face is similar to Gastly, though the two Pokémon are not related.

Gender differences

None.

Special abilities

Cloyster have strong defenses and moderate offenses, both thanks to their sturdy shell. They fight by clamping their shell tightly shut while launching spikes from their shell to strike opponents.

Behavior

Cloyster are sneaky and clever Pokémon, viciously rushing at prey while shooting spikes. They fight roughly because of the hostile nature of their habitat and the protection of their shell, allowing them to withstand physical blows easily. Cloyster swim by means of propulsion, doing so by first swallowing water, and then jetting it out toward the rear. Cloyster may also shoot spikes from their shell using the same system.

In the manga

In the Pokémon Adventures manga

First seen against Yellow in conjunction with her Dewgong. Later, in the battle on Cerise Island, it kept the voodoo dolls of Green and Sabrina (which kept their arms bound by an ice cuff) safely out of reach while Lorelei battled them. Although it initially seemed that with Green out cold, Sabrina stood little chance, she feigned attacking repeatedly and slowly sapped Cloyster's strength using Mega Drain, eventually fainting it. Lorelei realized this, and quickly took back the dolls.

Cloyster reappeared again in Lorelei's attempt to defend Seven Island. It is then remarked that Cloyster is the strongest fighter Lorelei has in her arsenal due to the tough shell it possesses, said to withstand the damage of a Napalm Bomb. However, though they fought valiantly and pushed Sird to her limits, ultimately the insidious villain won by having her Starmiecamouflage itself and attack where they couldn't defend.

The boss of Team Rocket, Giovanni, is shown in several rounds using Cloyster. He used it to freeze two Magmar after having a chat with Red. Then, when Red came to beat him, he used it to freeze Poli.

In the Pokémon Adventures manga, Cloyster is drawn by Mato as having a blue marking like a jewel on its head, beneath the spike. The official art by Ken Sugimori, however, does not. This is likely because the white circle seen on Cloyster's head in most early sprites was interpreted by Mato as a jewel, but was actually intended just to be glare. Satoshi Yamamoto, who took over starting at Volume 10, did not make the same error.